1. Field of the Invention
This invention relates to a braking apparatus associated with a lifting device and more particularly to a braking mechanism for a lifting apparatus for loading and unloading heavy objects to and from a van.
2. Description of Related Art
The use of vans for service intensive businesses has proliferated due to their great versatility. Plumbing contractors, appliance repair contractors and other labor intensive type of services have long used vans because of their unique convenience. Unlike the open beds of trucks, vans provide a covered enclosure which can be locked and secured, thereby protecting its contents. Shelving and storage containers may be mounted on the interior walls of the van and access to the interior is usually provided from the rear by adjoining doors which swing outward away from the van and by a sliding panel on the side of such vans. Very often, it is desirable to transport heavy machinery, appliances, or other cargo from a remote location back to the main warehouse or shop for further service.
There have been many commercial systems available for open trucks and vans which have hoist systems mounted thereto for facilitating the loading and unloading of the aforementioned heavy cargo. Hoist systems, in general, have been bulky thereby utilizing the great majority of a space within the van. One example of an apparatus for loading and unloading a van which includes a framework within the van is shown in U.S. Pat. No. 4,187,048. The hoist mechanism includes a beam which is slidably mounted within the van. The wench is movably disposed on the beam for allowing an object to be loaded by hoisting an object upwardly when the beam and the hoist extend out the rear of the van. The beam may be slid manually to a position within the van once the object is hoisted. Thereafter it can then be lowered to the floor of the van prior to transporting. In operation, the van is backed up to an object where the rear doors of the van are opened and the I-beam slid outwardly along an axis parallel to the length of the van. Both the winch and the sliding of the I-beam are manually operated. The problem with this type of hoist system is that it does not enable an object to be loaded through the side door of a van, and the operation of the winch and the control of the extension of the boom are manually controlled.
Another example of a hoist system is disclosed in U.S. Pat. No. 4,252,491. U.S. Pat. No. 4,252,491 shows a hoist for loading and unloading cargo through a side doorway of a van. The hoist system consists of a platform which may be lowered outside the vehicle wherein the object to be hoisted is moved onto the platform and the platform thereafter raised by an electric winch connected to the platform by cables. However, the problem with this type of system is that the object to be loaded into the van must be first positioned over the platform. However, it is often desirable to position the van relative to the object to be moved, to position the boom over the object, to lower a cable down to the object, lift the object, and then move the boom back into the interior of the van where the object can then be lowered.
Another exemplary system is U.S. Pat. No. 4,806,060, which is for hoisting a wheelchair for vehicle having a body, a roof, and a door opening. The hoist system comprises a support bar suspended from the roof of the van with a mount tube reciprocally mounted upon the support bar. A boom is mounted to the support tube. A reversible electric motor is supported upon the mount tube and drives a pinion and mesh with a stationary rack gear for reciprocally feeding the boom from its retracted position to an advance position through the door opening. However, this system has the problem that the support for the extendable boom is secured to the roof of the van by spaced hanger brackets. Therefore, the ability to lift heavy objects such as appliances is severely limited. Further the rack gear and motor would not provide sufficient torque to lift heavy appliances.
New methods have been devised for lifting and moving heavy objects into vans and the like which include a telescoping boom to facilitate loading and unloading. Further information on a lifting device having an extendable boom mechanism for loading and unloading heavy cargo from the side door of a van while maximizing lift capability, ease of use, and minimization of the interior area of the van is disclosed in the co-pending application Ser. No. 08/271,198 filed on Jul. 7, 1994, by the present applicants entitled "REMOTELY CONTROLLED EXTENDABLE LIFT APPARATUS FOR A VAN", which application is hereby incorporated by reference.
Nevertheless, since the such lifting devices are often used for lifting objects of great weight, inherent danger exits once the objects have been lifted or during the lifting process. For example the motor may fail during the lifting of the objects. In this situation, the object being lifted will crash to the ground possibly injuring the operator who may be trying to guide the object into the van.
Accordingly, it can be seen that there is a need for a break mechanism for a lifting apparatus to prevent injury to the operator.